Public Land Mobile Network Selection for Non-Terrestrial Networks

ABSTRACT

Systems, devices and methods for a user equipment (UE) to perform public land mobile network (PLMN) selection with a non-terrestrial network (NTN). A UE performs a non-access stratum (NAS) procedure with a public land mobile network (PLMN) of an NTN. The UE receives a NAS message from the PLMN, and the NAS message indicates that the UE is not allowed to access a core network of the NTN. The NAS message may indicate that the UE is not allowed to access the core network of the NTN because a location of the UE is unknown to the NTN, that access to the NTN is not allowed in a country in which the UE is located, or that a location of the UE is not within a country associated with the NTN. The UE modifies its PLMN search procedure responsive to receiving the NAS message.

PRIROITY DATA

This application claims benefit of priority to Indian Application No.202141001960, titled “Public Land Mobile Network Selection forNon-Terrestrial Networks”, filed Jan. 15, 2021, which is herebyincorporated by reference in its entirety as though fully and completelyset forth herein. The claims in the instant application are differentthan those of the parent application or other related applications. TheApplicant therefore rescinds any disclaimer of claim scope made in theparent application or any predecessor application in relation to theinstant application. The Examiner is therefore advised that any suchprevious disclaimer and the cited references that it was made to avoid,may need to be revisited. Further, any disclaimer made in the instantapplication should not be read into or against the parent application orother related applications

TECHNICAL FIELD

The present application relates to wireless devices, and moreparticularly to methods, apparatuses, and systems for a wireless devicecommunicating over a non-terrestrial cellular network and performingpublic land mobile network selection.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Wirelessdevices, particularly wireless user equipment devices (UEs), have becomewidespread. Additionally, people are becoming increasingly mobileincluding international travel. Non-terrestrial networks (NTNs) such as3GPP satellite networks have increased in usage, in particular duringinternational mobility scenarios. Accordingly, increased reliability andconnectivity for UEs using NTNs are desirable.

SUMMARY

Embodiments are presented herein of methods, apparatuses, and systemsfor a wireless device to perform public land mobile network (PLMN)selection with a non-terrestrial cellular network.

In some embodiments, a user equipment (UE) performs a first non-accessstratum (NAS) procedure with a first public land mobile network (PLMN)of a first non-terrestrial network (NTN). The UE receives a servicerejection, registration reject, or another similar non-access stratum(NAS) message from the first PLMN, where the NAS message indicates thatthe UE is not allowed to access a 5G cellular ore network of the firstNTN. The NAS message may further indicate that the UE is not allowed toaccess the core network of the first NTN because a location of the UE isunknown to the first NTN, that access to the first NTN is not allowed ina country in which the UE is located, or that a location of the UE isnot within a country associated with the first NTN.

In some embodiments, responsive to receiving the NAS (e.g., servicerejection) message, the UE performs a search to access a terrestrialcellular or non-cellular network. After successfully establishing aconnection with a first terrestrial network, the UE may perform a secondregistration procedure with the first PLMN, where the UE provides anidentifier of the first terrestrial network to the first NTN during thesecond registration procedure, and where the identifier is useable bythe first NTN to determine a location of the UE.

In some embodiments, responsive to receiving the NAS (e.g., servicerejection) message, the UE initiates a second NAS procedure with asecond PLMN of a second NTN belonging to a second country that isdifferent from a first country of the first NTN.

In some embodiments, a non-transitory memory medium may include programinstructions executable by a UE that, when executed, cause the UE toperform at least a portion or all of the above operations. In someembodiments, a method performed by the UE may include the UE performingthe above operations. In some embodiments, a method performed by a basestation or network element may include the base station or networkelement performing corresponding operations.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the disclosed embodiments can be obtained whenthe following detailed description is considered in conjunction with thefollowing drawings, in which:

FIG. 1 illustrates an example wireless communication system, accordingto some embodiments;

FIG. 2 illustrates a base station (BS) in communication with a userequipment (UE) device, according to some embodiments;

FIG. 3 illustrates an example block diagram of a UE, according to someembodiments;

FIG. 4 illustrates an example block diagram of a BS, according to someembodiments;

FIG. 5 is a network infrastructure diagram illustrating a 3GPP satellitenetwork deployment, according to some embodiments;

FIGS. 6A-B and schematic diagrams illustrating interworking between 3GPPterrestrial and satellite radio access networks (RANs), according tosome embodiments;

FIGS. 7A-D are different satellite deployment scenarios, according tovarious embodiments;

FIG. 8 is a communication flow diagram illustrating a method for a UE toattempt a registration procedure with a non-terrestrial network (NTN);

FIG. 9 is a flowchart diagram illustrating a method for a UE tocommunicate with a dedicated international area NTN;

FIGS. 10A-B are satellite deployment scenarios illustrating aprovisioned distance from a coverage area, according to variousembodiments; and

FIG. 11 is a schematic illustration of a UE on an airplane flightthrough a plurality of coverage areas, according to some embodiments.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to limit the invention to the particular formdisclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS Acronyms

The following acronyms are used in the present Patent Application:

SGCN: 5G Core Network SGMM: 5G Mobility Management AF: ApplicationFunction NAS: Non-Access Stratum NF: Network Function AMF: Access andMobility Management Function CP: Control Plane DN: Data Network DNAI:Data Network Access Identifier HO: Handover PLMN: Public Land MobileNetwork HPPLMN: Higher Priority PLMN UPLMN/OPLMN/VPLMN:User/Operator/Visited PLMN LEO/MEO: Low/Medium Earth Orbit GEO:Geosynchronous Equatorial Orbit MCC: Mobile Country Code NTN:Non-terrestrial Network PCF: Policy Control Function PDU: Protocol DataUnit TA: Tracking Area UDM: Unified Data Management UDR: Unified DataRepository UPF: User Plane Function UE: User Equipment BS: Base Station

eNB: eNodeB (Base Station)

LTE: Long Term Evolution UMTS: Universal Mobile TelecommunicationsSystem RAT: Radio Access Technology RAN: Radio Access Network E-UTRAN:Evolved UMTS Terrestrial RAN EPC: Evolved Packet Core MME: MobileManagement Entity RRC: Radio Resource Control BWP: Bandwidth Part TCI:Transmission Configuration Indicator FDM: Frequency DivisionMultiplexing SSB: Synchronization Signal Block MAC: Medium AccessControl CE: Control Element DCI: Downlink Control Information QCL:Quasi-Colocated PDCCH: Physical Downlink Control Channel PDSCH: PhysicalDownlink Shared Channel DL: Downlink RSRP: Reference Signal ReceivePower L1: Layer-1 HARQ: Hybrid Automatic Repeat Request NR: New RadioTerms

The following is a glossary of terms used in the present application:

Memory Medium—Any of various types of memory devices or storage devices.The term “memory medium” is intended to include an installation medium,e.g., a CD-ROM, floppy disks 104, or tape device; a computer systemmemory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM,Rambus RAM, etc.; a non-volatile memory such as a Flash, magnetic media,e.g., a hard drive, or optical storage; registers, or other similartypes of memory elements, etc. The memory medium may comprise othertypes of memory as well or combinations thereof. In addition, the memorymedium may be located in a first computer in which the programs areexecuted, or may be located in a second different computer whichconnects to the first computer over a network, such as the Internet. Inthe latter instance, the second computer may provide programinstructions to the first computer for execution. The term “memorymedium” may include two or more memory mediums which may reside indifferent locations, e.g., in different computers that are connectedover a network.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems or devices that are mobile or portable and that perform wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), tablet computers(e.g., iPad™, Samsung Galaxy™), portable gaming devices (e.g., NintendoDS™, PlayStation Portable™, Gameboy Advance™, iPhone™), wearable devices(e.g., smart watch, smart glasses), laptops, PDAs, portable Internetdevices, music players, data storage devices, other handheld devices,automobiles and/or motor vehicles, unmanned aerial vehicles (UAVs)(e.g., drones), UAV controllers (UACs), etc. In general, the term “UE”or “UE device” can be broadly defined to encompass any electronic,computing, and/or telecommunications device (or combination of devices)which is easily transported by a user and capable of wirelesscommunication.

Processing Element—refers to various elements or combinations ofelements that are capable of performing a function in a device, such asa user equipment or a cellular network device. Processing elements mayinclude, for example: processors and associated memory, portions orcircuits of individual processor cores, entire processor cores,processor arrays, circuits such as an ASIC (Application SpecificIntegrated Circuit), programmable hardware elements such as a fieldprogrammable gate array (FPGA), as well any of various combinations ofthe above.

FIGS. 1 and 2—Communication System

FIG. 1 illustrates a simplified example wireless communication system,according to some embodiments. It is noted that the system of FIG. 1 ismerely one example of a possible system, and that features of thisdisclosure may be implemented in any of various systems, as desired.

As shown, the example wireless communication system includes a basestation 102 which communicates over a transmission medium with one ormore user devices 106A, 106B, etc., through 106N. Each of the userdevices may be referred to herein as a “user equipment” (UE). Thus, theuser devices 106 are referred to as UEs or UE devices.

The base station (BS) 102 may be a base transceiver station (BTS) orcell site (a “cellular base station”), and may include hardware thatenables wireless communication with the UEs 106A through 106N.

The communication area (or coverage area) of the base station may bereferred to as a “cell.” The base station 102 and the UEs 106 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs), also referred to as wirelesscommunication technologies, or telecommunication standards, such as GSM,UMTS (associated with, for example, WCDMA or TD-SCDMA air interfaces),LTE, LTE-Advanced (LTE-A), 5G new radio (5G NR), 5G NR satellite access(5G NR SAT), 6G, HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD,eHRPD), etc. Note that if the base station 102 is implemented in thecontext of LTE, it may alternately be referred to as an ‘eNodeB’ or‘eNB’. Note that if the base station 102 is implemented in the contextof 5G NR, it may alternately be referred to as ‘gNodeB’ or ‘gNB’.

As shown, the base station 102 may also be equipped to communicate witha network 100 (e.g., a core network of a cellular service provider, atelecommunication network such as a public switched telephone network(PSTN), and/or the Internet, among various possibilities). Thus, thebase station 102 may facilitate communication between the user devicesand/or between the user devices and the network 100. In particular, thecellular base station 102 may provide UEs 106 with varioustelecommunication capabilities, such as voice, SMS and/or data services.

Base station 102 and other similar base stations operating according tothe same or a different cellular communication standard may thus beprovided as a network of cells, which may provide continuous or nearlycontinuous overlapping service to UEs 106A-N and similar devices over ageographic area via one or more cellular communication standards.

Thus, while base station 102 may act as a “serving cell” for UEs 106A-Nas illustrated in FIG. 1, each UE 106 may also be capable of receivingsignals from (and possibly within communication range of) one or moreother cells (which might be provided by other base stations 102B-N),which may be referred to as “neighboring cells”. Such cells may also becapable of facilitating communication between user devices and/orbetween user devices and the network 100. Such cells may include “macro”cells, “micro” cells, “pico” cells, and/or cells which provide any ofvarious other granularities of service area size. Other configurationsare also possible.

In some embodiments, base station 102 may be a next generation basestation, e.g., a 5G New Radio (5G NR) base station, or “gNB”. In someembodiments, a gNB may be connected to a legacy evolved packet core(EPC) network and/or to a NR core (NRC) network. In addition, a gNB cellmay include one or more transition and reception points (TRPs). Inaddition, a UE capable of operating according to 5G NR may be connectedto one or more TRPs within one or more gNBs.

Note that a UE 106 may be capable of communicating using multiplewireless communication standards. For example, the UE 106 may beconfigured to communicate using a wireless networking (e.g., Wi-Fi)and/or peer-to-peer wireless communication protocol (e.g., Bluetooth,Wi-Fi peer-to-peer, etc.) in addition to at least one cellularcommunication protocol (e.g., GSM, UMTS (associated with, for example,WCDMA or TD-SCDMA air interfaces), LTE, LTE-A, 5G NR, 5G NR SAT, HSPA,3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), etc.). The UE 106may also or alternatively be configured to communicate using one or moreglobal navigational satellite systems (GNSS, e.g., GPS or GLONASS), oneor more mobile television broadcasting standards (e.g., ATSC-M/H),and/or any other wireless communication protocol, if desired. Othercombinations of wireless communication standards (including more thantwo wireless communication standards) are also possible.

FIG. 2 illustrates user equipment 106 (e.g., one of the devices 106Athrough 106N) in communication with a base station 102, according tosome embodiments. The UE 106 may be a device with cellular communicationcapability such as a mobile phone, a hand-held device, a computer or atablet, or virtually any type of wireless device.

The UE 106 may include a processor that is configured to execute programinstructions stored in memory. The UE 106 may perform any of the methodembodiments described herein by executing such stored instructions.Alternatively, or in addition, the UE 106 may include a programmablehardware element such as an FPGA (field-programmable gate array) that isconfigured to perform any of the method embodiments described herein, orany portion of any of the method embodiments described herein.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols or technologies. In someembodiments, the UE 106 may be configured to communicate using, forexample, CDMA2000 (1xRTT/1xEV-DO/HRPD/eHRPD) or LTE using a singleshared radio and/or GSM or LTE using the single shared radio. The sharedradio may couple to a single antenna, or may couple to multiple antennas(e.g., for multiple-input, multiple-output or “MIMO”) for performingwireless communications. In general, a radio may include any combinationof a baseband processor, analog RF signal processing circuitry (e.g.,including filters, mixers, oscillators, amplifiers, etc.), or digitalprocessing circuitry (e.g., for digital modulation as well as otherdigital processing). Similarly, the radio may implement one or morereceive and transmit chains using the aforementioned hardware. Forexample, the UE 106 may share one or more parts of a receive and/ortransmit chain between multiple wireless communication technologies,such as those discussed above.

In some embodiments, the UE 106 may include any number of antennas andmay be configured to use the antennas to transmit and/or receivedirectional wireless signals (e.g., beams). Similarly, the BS 102 mayalso include any number of antennas and may be configured to use theantennas to transmit and/or receive directional wireless signals (e.g.,beams). To receive and/or transmit such directional signals, theantennas of the UE 106 and/or BS 102 may be configured to applydifferent “weight” to different antennas. The process of applying thesedifferent weights may be referred to as “precoding”.

In some embodiments, the UE 106 may include separate transmit and/orreceive chains (e.g., including separate antennas and other radiocomponents) for each wireless communication protocol with which it isconfigured to communicate. As a further possibility, the UE 106 mayinclude one or more radios which are shared between multiple wirelesscommunication protocols, and one or more radios which are usedexclusively by a single wireless communication protocol. For example,the UE 106 might include a shared radio for communicating using eitherof LTE or 5G NR (or LTE or 1xRTTor LTE or GSM), and separate radios forcommunicating using each of Wi-Fi and Bluetooth. Other configurationsare also possible.

FIG. 3—Block Diagram of a UE

FIG. 3 illustrates an example simplified block diagram of acommunication device 106, according to some embodiments. It is notedthat the block diagram of the communication device of FIG. 3 is only oneexample of a possible communication device. According to embodiments,communication device 106 may be a user equipment (UE) device, a mobiledevice or mobile station, a wireless device or wireless station, adesktop computer or computing device, a mobile computing device (e.g., alaptop, notebook, or portable computing device), a tablet and/or acombination of devices, among other devices. As shown, the communicationdevice 106 may include a set of components 300 configured to performcore functions. For example, this set of components may be implementedas a system on chip (SOC), which may include portions for variouspurposes. Alternatively, this set of components 300 may be implementedas separate components or groups of components for the various purposes.The set of components 300 may be coupled (e.g., communicatively;directly or indirectly) to various other circuits of the communicationdevice 106.

For example, the communication device 106 may include various types ofmemory (e.g., including NAND flash 310), an input/output interface suchas connector I/F 320 (e.g., for connecting to a computer system; dock;charging station; input devices, such as a microphone, camera, keyboard;output devices, such as speakers; etc.), the display 360, which may beintegrated with or external to the communication device 106, andcellular communication circuitry 330 such as for 5G NR, LTE, GSM, etc.,and short to medium range wireless communication circuitry 329 (e.g.,Bluetooth™ and WLAN circuitry). In some embodiments, communicationdevice 106 may include wired communication circuitry (not shown), suchas a network interface card, e.g., for Ethernet.

The cellular communication circuitry 330 may couple (e.g.,communicatively; directly or indirectly) to one or more antennas, suchas antennas 335 and 336 as shown. The short to medium range wirelesscommunication circuitry 329 may also couple (e.g., communicatively;directly or indirectly) to one or more antennas, such as antennas 337and 338 as shown. Alternatively, the short to medium range wirelesscommunication circuitry 329 may couple (e.g., communicatively; directlyor indirectly) to the antennas 335 and 336 in addition to, or insteadof, coupling (e.g., communicatively; directly or indirectly) to theantennas 337 and 338. The short to medium range wireless communicationcircuitry 329 and/or cellular communication circuitry 330 may includemultiple receive chains and/or multiple transmit chains for receivingand/or transmitting multiple spatial streams, such as in amultiple-input multiple output (MIMO) configuration.

In some embodiments, as further described below, cellular communicationcircuitry 330 may include dedicated receive chains (including and/orcoupled to, e.g., communicatively, directly or indirectly, dedicatedprocessors and/or radios) for multiple RATs (e.g., a first receive chainfor LTE and a second receive chain for 5G NR). In addition, in someembodiments, cellular communication circuitry 330 may include a singletransmit chain that may be switched between radios dedicated to specificRATs. For example, a first radio may be dedicated to a first RAT, e.g.,LTE, and may be in communication with a dedicated receive chain and atransmit chain shared with an additional radio, e.g., a second radiothat may be dedicated to a second RAT, e.g., 5G NR, and may be incommunication with a dedicated receive chain and the shared transmitchain.

The communication device 106 may also include and/or be configured foruse with one or more user interface elements. The user interfaceelements may include any of various elements, such as display 360 (whichmay be a touchscreen display), a keyboard (which may be a discretekeyboard or may be implemented as part of a touchscreen display), amouse, a microphone and/or speakers, one or more cameras, one or morebuttons, and/or any of various other elements capable of providinginformation to a user and/or receiving or interpreting user input.

The communication device 106 may further include one or more smart cards345 that include SIM (Subscriber Identity Module) functionality, such asone or more UICC(s) (Universal Integrated Circuit Card(s)) cards 345.

As shown, the SOC 300 may include processor(s) 302, which may executeprogram instructions for the communication device 106 and displaycircuitry 304, which may perform graphics processing and provide displaysignals to the display 360. The processor(s) 302 may also be coupled tomemory management unit (MMU) 340, which may be configured to receiveaddresses from the processor(s) 302 and translate those addresses tolocations in memory (e.g., memory 306, read only memory (ROM) 350, NANDflash memory 310) and/or to other circuits or devices, such as thedisplay circuitry 304, short range wireless communication circuitry 229,cellular communication circuitry 330, connector I/F 320, and/or display360. The MMU 340 may be configured to perform memory protection and pagetable translation or set up. In some embodiments, the MMU 340 may beincluded as a portion of the processor(s) 302.

As noted above, the communication device 106 may be configured tocommunicate using wireless and/or wired communication circuitry. Thecommunication device 106 may be configured to transmit a request toattach to a first network node operating according to the first RAT andtransmit an indication that the wireless device is capable ofmaintaining substantially concurrent connections with the first networknode and a second network node that operates according to the secondRAT. The wireless device may also be configured transmit a request toattach to the second network node. The request may include an indicationthat the wireless device is capable of maintaining substantiallyconcurrent connections with the first and second network nodes. Further,the wireless device may be configured to receive an indication that dualconnectivity (DC) with the first and second network nodes has beenestablished.

As described herein, the communication device 106 may include hardwareand software components for implementing features for using multiplexingto perform transmissions according to multiple radio access technologiesin the same frequency carrier (e.g., and/or multiple frequencycarriers), as well as the various other techniques described herein. Theprocessor 302 of the communication device 106 may be configured toimplement part or all of the features described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively (or inaddition), processor 302 may be configured as a programmable hardwareelement, such as an FPGA (Field Programmable Gate Array), or as an ASIC(Application Specific Integrated Circuit). Alternatively (or inaddition) the processor 302 of the communication device 106, inconjunction with one or more of the other components 300, 304, 306, 310,320, 329, 330, 340, 345, 350, 360 may be configured to implement part orall of the features described herein.

In addition, as described herein, processor 302 may include one or moreprocessing elements. Thus, processor 302 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processor 302. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processor(s) 302.

Further, as described herein, cellular communication circuitry 330 andshort-range wireless communication circuitry 329 may each include one ormore processing elements and/or processors. In other words, one or moreprocessing elements or processors may be included in cellularcommunication circuitry 330 and, similarly, one or more processingelements or processors may be included in short range wirelesscommunication circuitry 329. Thus, cellular communication circuitry 330may include one or more integrated circuits (ICs) that are configured toperform the functions of cellular communication circuitry 330. Inaddition, each integrated circuit may include circuitry (e.g., firstcircuitry, second circuitry, etc.) configured to perform the functionsof cellular communication circuitry 330. Similarly, the short-rangewireless communication circuitry 329 may include one or more ICs thatare configured to perform the functions of short-range wirelesscommunication circuitry 329. In addition, each integrated circuit mayinclude circuitry (e.g., first circuitry, second circuitry, etc.)configured to perform the functions of short-range wirelesscommunication circuitry 329.

FIG. 4—Block Diagram of a Base Station

FIG. 4 illustrates an example block diagram of a base station 102,according to some embodiments. It is noted that the base station of FIG.4 is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 404 which may execute programinstructions for the base station 102. The processor(s) 404 may also becoupled to memory management unit (MMU) 440, which may be configured toreceive addresses from the processor(s) 404 and translate thoseaddresses to locations in memory (e.g., memory 460 and read only memory(ROM) 450) or to other circuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above in FIGS. 1 and 2.

The network port 470 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 470may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

In some embodiments, base station 102 may be a next generation basestation, e.g., a 5G New Radio (5G NR) base station, or “gNB”. In suchembodiments, base station 102 may be connected to a legacy evolvedpacket core (EPC) network and/or to a NR core (NRC) network. Inaddition, base station 102 may be considered a 5G NR cell and mayinclude one or more transition and reception points (TRPs). In addition,a UE capable of operating according to 5G NR may be connected to one ormore TRPs within one or more gNBs.

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The radio 430 and at least one antenna 434 may beconfigured to operate as a wireless transceiver and may be furtherconfigured to communicate with UE devices 106. The antenna 434 maycommunicate with the radio 430 via communication chain 432.Communication chain 432 may be a receive chain, a transmit chain orboth. The radio 430 may be configured to communicate via variouswireless communication standards, including, but not limited to, 5G NR,5G NR SAT, LTE, LTE-A, GSM, UMTS, CDMA2000, Wi-Fi, etc.

The base station 102 may be configured to communicate wirelessly usingmultiple wireless communication standards. In some instances, the basestation 102 may include multiple radios, which may enable the basestation 102 to communicate according to multiple wireless communicationtechnologies. For example, as one possibility, the base station 102 mayinclude an LTE radio for performing communication according to LTE aswell as a 5G NR radio for performing communication according to 5G NR.In such a case, the base station 102 may be capable of operating as bothan LTE base station and a 5G NR base station. As another possibility,the base station 102 may include a multi-mode radio which is capable ofperforming communications according to any of multiple wirelesscommunication technologies (e.g., 5GNR and Wi-Fi, 5GNR SAT and Wi-Fi,LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.).

As described further subsequently herein, the BS 102 may includehardware and software components for implementing or supportingimplementation of features described herein. The processor 404 of thebase station 102 may be configured to implement or supportimplementation of part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof. Alternatively(or in addition) the processor 404 of the BS 102, in conjunction withone or more of the other components 430, 432, 434, 440, 450, 460, 470may be configured to implement or support implementation of part or allof the features described herein.

In addition, as described herein, processor(s) 404 may include one ormore processing elements. Thus, processor(s) 404 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processor(s) 404. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processor(s) 404.

Further, as described herein, radio 430 may include one or moreprocessing elements. Thus, radio 430 may include one or more integratedcircuits (ICs) that are configured to perform the functions of radio430. In addition, each integrated circuit may include circuitry (e.g.,first circuitry, second circuitry, etc.) configured to perform thefunctions of radio 430.

FIGS. 5-6—3GPP Satellite Network Infrastructure

FIG. 5 is a network infrastructure diagram illustrating a 3GPP satellitenetwork deployment, according to some embodiments. As illustrated, asatellite broadcasts a service link to a UE, such as UE 106, where theUE is operating within a cell. The satellite also conductscommunications with a terrestrial gateway via a feeder link, and thegateway is in turn communicatively coupled to a base station (e.g., agNB). The base station comprises a distributed unit (DU) and acentralized unit (CU). The base station is then coupled to a 5G CoreNetwork (5GC) with a tracking area code (TAC) via an N2 interface.

FIGS. 6A-B and schematic diagrams illustrating interworking between 3GPPterrestrial and satellite radio access networks (RANs), according tosome embodiments. As illustrated, in FIG. 6A, a UE 106 communicates witha 3GPP terrestrial RAN, e.g., through a gNB as shown in FIGS. 1-2. The3GPP terrestrial RAN is coupled via an N2 interface with a core network,and a 3GPP satellite RAN is also coupled to the core network via the N2interface. FIG. 6B illustrates a UE 106 operating with a cell to obtain3GPP terrestrial access. The UE 106 also operates within a broadergeographic range that provides 3GPP satellite access.

Public Land Mobile Networks

In cellular communications, cellular service providers or carriers mayprovide cellular service through public land mobile networks (PLMNs).While PLMNs are typically associated with cellular communications, it isanticipated that 5G NR may utilize PLMNs for servicing satellitenetworks, also known as non-terrestrial networks (NTNs). Embodimentsherein describe methods and devices for improving communications andpreserving regulatory compliance in association with PLMN selection forNTNs. As used herein, NTNs are contrasted with “terrestrial networks”,which include both cellular and non-3GPP (e.g., wireless local areanetwork (WLAN)) networks.

Cellular service providers typically control their subscribers' wirelessdevices' roaming behavior by providing a user-preferred public landmobile network (UPLMN) list and an operator-defined public land mobilenetwork (OPLMN) list. The UPLMN and/or OPLMN list may be stored inelementary files in the SIM card, and may specify PLMN-radio accesstechnology (RAT) relative priorities, which may be influenced or definedby roaming agreements between the operator providing the UPLMN/OPLMNlist and operators of other PLMNs. PLMNs included in the UPLMN/OPLMNlist may also be referred to as preferred PLMNs (PPLMNs). A UE mayselect and register on a PLMN and RAT from the PPLMN list when roaminge.g., in order to quickly acquire service from a suitable serviceprovider.

It is possible that a UPLMN/OPLMN may not be available in a roamingscenario, and a possible fallback option may be for the UE to randomlyselect an available PLMN or select the PLMN with the strongest signalstrength and try to register. However, with such a random selection,there may be a significant likelihood that the visited PLMN (VPLMN) mayreject the registration request, or try to push the UE away withsteering, which may cause a significant delay for the UE to acquireservice.

Some legacy implementations for ranking PLMN selection employ aplurality of tiers of PLMN lists, which a UE may utilize to determine anorder of PLMNs upon which to attempt to camp (for example, when a UEmoves to a new region and attempts to reestablish cellular service). Insome legacy implementations, when a UE is switched on at a new location(e.g., within a new circle), an initial search is performed based on aregistered PLMN (RPLMN), with valid location information of the RPLMNcontained in a subscriber identity module (SIM) card of the UE. Forexample, the initial UE search may include a short list search (SLS) anda derived band search (DBS) on all supported technologies.

Wireless communication deployments that contain both cellular and NTNPLMNs introduce additional complications for PLMN selection. Embodimentsherein present systems and methods to address these and otherchallenges.

PLMN Selection for NTN Access

FIGS. 6A-D illustrate four different satellite deployment scenarios,according to some embodiments. In FIGS. 6A-D, the shaded ovals indicatesatellite coverage areas, whereas the unshaded circles represent countryand other area boundaries.

FIG. 6A illustrates deployment scenario A. As illustrated, a satelliteprovides a cell that broadcasts signals to country A, but the coveragearea unintentionally leaks across the border of country A to cover aportion of adjacent countries B and C. The PLMN identifier (ID)broadcast in the cell of FIG. 6A has a mobile country code (MCC)corresponding to Country A.

FIG. 6B illustrates deployment scenario B, where a satelliteintentionally services countries A, B and C but the coverage areaunintentionally leaks into country D. Scenario B may be deployed inseveral different ways, according to various embodiments. As a firstpossibility (scenario B1), the satellite may broadcast three PLMN IDswith three different MCCs corresponding to countries A, B and C. In thisscenario, the PLMN operator may be registered and obtain a mobilenetwork code (MNC) in each country. In this scenario, it may bedesirable for a UE to intelligently choose the MCC corresponding to thecountry of either its HPLMN or the physical location of the UE, to avoidaccessing a neighboring country's MCC. For example, the UE may be closeto a border between two countries (e.g., the Germany-Austria border),and it may be desirable for the UE to avoid accessing satellites of theneighboring country near border locations. To address these and otherconcerns, during a PLMN selection procedure for NTN access, if a UEdiscovers two or more MCCs during the PLMN scan and one of the MCCsbelongs to the HPLMN of the UE, the UE may generally prioritizeselection of the MCC that belongs to the HPLMN. In other embodiments,when the UE is able to detect the country where it is currently located,e.g. via GPS techniques, the UE may select the PLMN belonging to the MCCwhere the UE is physically located. However, the UE may implementexceptions to this general prioritization under certain conditions. Forexample, the UE may only prioritize the HPLMN MCC as long as it iswithin a predetermined distance from the border of the country of theMCC and/or if the UE is below a predetermined mobility threshold.Alternatively, the UE may prioritize the HPLMN MCC as long as the RSRPof the HPLMN MCC is above a predetermined threshold, such as −115 dBm oranother threshold. Alternatively, the UE may always attempt registrationon the HPLMN MCC for a predetermined number of attempts (e.g., 5attempts), and may attempt registration on other available MCCs if theregistration attempt fails the predetermined number of times. In someembodiments, if registration on the HPLMN MCC is unsuccessful thepredetermined number of times, the UE may receive prioritized list(s) ofPLMNs from a system information block (SIB) broadcast message receivedfrom the network, and may perform a PLMN search based on the prioritylist. In some embodiments, the broadcast message may contain a polygongeofence or coordinates describing a geographical area within which eachof one or more priority rankings are to take effect.

As another possibility (scenario B2), a single PLMN ID corresponding toone country (e.g., country A) may be broadcast, and extra-territorialuse of the PLMN ID, along with the conditions for such use, may bedefined by communications standards. In this scenario, during a PLMNselection procedure, if a UE is unable to determine the exact countrywhere the UE is located (e.g., when the UE is close to a border anddoesn't have sufficiently accurate location information), the UE mayrequest to register with an NTN PLMN by first providing its presumedlocation as country A (its home country).

As a third possibility (scenario B3), a global/shared PLMN ID (e.g.,with a MCC 9xx) may be broadcast. Mechanisms for servicing global/sharedPLMN IDs, are described in greater detail below.

FIG. 6C illustrates another deployment scenario (scenario C), where asatellite access cell spans across a country (country A) and itscontiguous area (e.g., water or airspace) and leaks into an adjacentinternational area. In this scenario, the PLMN ID broadcast in the cellmay have an MCC of country A. In some embodiments, in this deploymentscenario, a UE with a home PLMN (HPLMN) of country A may move into theinternational area. The UE may determine that it is in the internationalarea through a network-provided database or an internal databasemaintained in UE memory or in the UE SIM card, among otherpossibilities. The UE may then calculate its distance from the boundaryof country A's contiguous area. If the calculated distance is greaterthan a threshold distance and/or if the remaining battery life of the UEis above a threshold, the UE may utilize a shorter interval forperforming higher priority PLMN searches. Alternatively, if thecalculated distance is less than the threshold distance and/or theremaining battery life of the UE is below a threshold, the UE mayutilize a longer interval for performing higher priority PLMN searches.Said another way, the UE may configure the interval for performingsubsequent higher priority PLMN searches to be shorter or longer than adefault interval depending on one or more of the above criteria.

FIG. 6D illustrates another deployment scenario (scenario D), where asatellite that is dedicated to an international area provides a cellthat leaks into an adjacent country and/or its contiguous area. ScenarioD may be deployed in several different ways, according to variousembodiments. As a first possibility (scenario D1), the PLMN ID broadcastin the cell is a global/shared PLMN ID (with MCC 9xx). As a secondpossibility (scenario D2), the PLMN ID broadcast in the cell is the PLMNID of the operator of the PLMN, and the MCC may be the MCC of the homecountry of the PLMN.

Lawful Interception Regulations

In some areas, lawful interception (LI) regulations have established therequirement to “enforce the use of a Core Network (CN) of a PLMN in thecountry where the UE is physically located”. The requirement that theselected PLMN must have a core network in the same country may presentchallenges for the UE during the PLMN selection procedure. The corenetwork location verification may take place during the registrationprocedure (by AS or NAS). However, from the protocol efficiency andresource utilization efficiency point of view, it may be advantageousfor the UE to still select a PLMN in a way that reduces the possibilityof registration rejection due to a registration attempt in the wrongcountry.

Embodiments herein present devices and methods for a UE to determinewhich PLMN(s) to select in the country of its physical location, tosatisfy the LI requirements of that country. Alternatively,international areas (e.g., international waters) typically do not haveLI requirements, and alternative mechanisms for PLMN selection for NTNaccess may be utilized when a UE is located in an international area. Invarious embodiments, the selection criteria may be pre-configured in theUE or provided by a PLMN.

NTN Registration Rejection

In some embodiments, it may be desirable to limit a UE's PLMN selectionto consider only PLMN candidates belonging to one country. When a UEsends a Registration request to an AMF not serving the country where theUE is located, the AMF may send a DE-REGISTRATION REQUEST, aREGISTRATION REJECT message, or another NAS message. In someembodiments, the AMF may additionally indicate to the UE in theDE-REGISTRATION REQUEST, REGISTRATION REJECT, or other NAS message thatthe UE should select a PLMN in different country. The AMF mayadditionally indicate a target MCC List (e.g. based on UE location) inthe DE-REGISTRATION REQUEST, REGISTRATION REJECT or other NAS message,to assist the UE in PLMN selection. In some embodiments, a UE which isalready registered with the PLMN in country A has now moved to countryB. In such cases, AMF, based on detection of UE's physical location mayproactively send a DEREGISTRATION REQUEST message.

In some embodiments, a UE which is not provisioned for NTN access by theregulatory and/or network requirements of the country where it islocated may have its registration request to a first PLMN for NTN accessrejected by the network. In these embodiments, it may advantageous forthe network to provide additional information to the UE along with itsregistration reject message. For example, the network may respond with areject cause indication that specifies (at least in part) the reason forthe rejection.

5G Mobility Management (5GMM)/Reject cause (a): As a first possibility,a first NTN may specify that NTN next generation radio access network(NG-RAN) access to the 5G core network (5GC) is not allowed. This maysignify that the 5GC on the first NTN and/or on the first PLMN do notallow satellite NG-RAN access to the UE. In response, the UE may stopattempting search and registration/reselection for NTN access on thefirst PLMN and may reselect to NG-RAN on a different PLMN for NTN accessand/or search for terrestrial 3GPP and/or non-3GPP access on the samePLMN.

In some embodiments, the UE may reset its behavior (i.e., if may resumea PLMN search for NTN access, including potentially attempting toregister on the first PLMN) when a particular condition is met, e.g.,when the UE powers off and on again, airplane mode toggles on and off,the user subscriber identity module (USIM) of the UE is removed, or theUE is registered to another PLMN, among other possibilities.

5GMM/Reject cause (b): As a second possibility, the first NTN mayspecify that satellite NG-RAN access to the 5GC is not allowed becausethe first NTN does not know the location at a country level of the UEthat is requesting access. This reject cause may be provided when UEaccess and mobility context information (specifically locationinformation) is not available in the UE context at the AMF. Responsiveto receiving a 5GMM/Reject cause (b), the UE may disable attempts toacquire NTN NG-RAN access and may search for an available terrestrial3GPP and/or non-3GPP access network (e.g., cellular or WiFi, among otherpossibilities). If the UE successfully registers and obtains access to aterrestrial network, and if the NTN PLMN access is of higher priority,the UE may then reattempt registration with the first NTN through thefirst PLMN, as the UE may provide location information via the RANthrough the UE context based on its connection with the terrestrialnetwork. The UE may resume attempts to obtain NTN access via a PLMNafter the UE is successfully registered over terrestrial 3GPP and/ornon-3GPP access, when it powers off and powers on again, when it togglesairplane mode on and off, or when the USIM is removed, among otherpossibilities.

5GMM/Reject cause (c): As a third possibility, the first NTN may specifythat NTN NG-RAN access is not allowed in the country where the UE islocated. For example, NTN NG-RAN access may be prohibited due toregulatory requirements of the country. This may signify that the UEshould not search or attempt on any PLMN via NTN NG-RAN while it is inthis country. As another example, the UE may be accessing the PLMN of adifferent MCC than the MCC where the UE is physically located.Responsive to receiving a reject cause (c), the UE may disable attemptsto acquire NTN NG-RAN access for all PLMNs belonging to the same MCCwhere it received the rejection, and the UE may search for an availableterrestrial 3GPP and/or non-3GPP access network (e.g., cellular or WiFi,among other possibilities). The UE may resume attempts to obtain NTNaccess via a PLMN after the UE powers off and powers on again, or whenit physically moves to another country, among other possibilities. TheUE may also attempt NTN NG-RAN access via a PLMN belonging to adifferent MCC in the same country.

5GMM/Reject cause (d): As a fourth possibility, the first NTN mayspecify that there is a mismatch between the location at a country levelof the UE and the country associated with the first NTN. For example,the UE may have sent a request to a 5GC in a country that doesn't servethe current location of the UE, and the first NTN may redirect orprovide information to the UE to attempt NTN access on a differentcountry's NTN. The information may include list of MCCs where the UE mayattempt re-registration while the UE continues to be in the samecountry. For example, the UE may be in a neighboring country that hasoverlapping coverage with the NTN cell of the country associated withthe first NTN. Responsive to receiving a 5GMM/reject cause (d), the UEmay mark NTN access to the NG-RAN as disabled for the MCC of the firstNTN, and may initiate a PLMN search for one or more other NTNs. In someembodiments, the UE may perform registration for NTN access on a PLMNassociated with an MCC indicated by the network in the registrationrejection message.

In some embodiments, 5GMM/reject cause (a) may be set as a “default”5GMM/reject cause, and 5GMM/reject causes (b), (c) and (d) may beindicated as extended 5GMM satellite cause code information elements(IEs), appended to the 5GMM/reject cause (a). Alternately, these5GMM/reject causes may be used with available 5GMM causes.

FIG. 7—Call Flow Diagram for NTN Access Rejection

FIG. 7 is a call flow diagram illustrating a method wherein a UErequests registration to a first NTN through an AMF and receives aservice rejection or registration rejection, according to someembodiments.

Aspects of the method of FIG. 7 may be implemented by a wireless device,such as the UE(s) 106, in communication with a network, e.g., via one ormore base stations (e.g., BS 102) as illustrated in and described withrespect to the Figures, or more generally in conjunction with any of thecomputer systems or devices shown in the Figures, among other circuitry,systems, devices, elements, or components shown in the Figures, amongother devices, as desired. For example, one or more processors (orprocessing elements) of the UE (e.g., processor(s) 302, basebandprocessor(s), processor(s) associated with communication circuitry,etc., among various possibilities) may cause the UE to perform some orall of the illustrated method elements. Similarly, one or moreprocessors (or processing elements) of the BS (e.g., processor(s) 404,baseband processor(s), processor(s) associated with communicationcircuitry, etc., among various possibilities) may cause the UE toperform some or all of the illustrated method elements. In someembodiments, the UE may communicate directly with a base station, andthe base station may in turn communicate with an access mobilityfunction (AMF) of a 5GC that services the PLMN of the NTN. Note thatwhile at least some elements of the method are described in a mannerrelating to the use of communication techniques and/or featuresassociated with 3GPP specification documents, such description is notintended to be limiting to the disclosure, and aspects of the method maybe used in any suitable wireless communication system, as desired. Invarious embodiments, some of the elements of the methods shown may beperformed concurrently, in a different order than shown, may besubstituted for by other method elements, or may be omitted. Additionalmethod elements may also be performed as desired. As shown, the methodmay operate as follows.

At 702, a UE initiates a non-access stratum (NAS) procedure with a firstPLMN of a first NTN. The NAS procedure may be an initial registrationprocedure, a mobility registration update procedure or a service requestprocedure, among other possibilities. In initiating the NAS procedure,the UE sends NAS request message to the first PLMN of the first NTN. TheNAS request message may be a mobility registration update procedure or aservice request, among other possibilities. The first PLMN may be a homePLMN (HPLMN) or visited PLMN (VPLMN) of the UE. The first PLMN may beserviced by an AMF. The NAS request message may be sent as part of afirst registration procedure with the first PLMN.

The AMF may determine location information of the UE from the requestreceived from the UE, and at 704 the AMF sends a NUDM subscriber datamanagement (SDM) Get Request message including the location informationto the unified data management (UDM). The UDM may be part of a corenetwork, such as a 5G Core Network (5GC). The UDM determines that the UEis not subscribed to 5GC NTN access in this location or that the UElocation is not within the country or countries covered by the 5GC, andat 706 responds to the AMF with a NUDM SDM Get Response message with(optionally) redirect MCC information. The redirect MCC information mayinclude information related to one or more MCCs associated with NTNsother than the first NTN for which the UE may be eligible to obtainnetwork access.

At 708, the AMF sends a NAS response message to the UE with a rejectcause indicator. The NAS response message may be a service rejectionmessage, a registration rejection message, or a deregistration requestmessage, among other possibilities. The NAS response message 708 mayoptionally contain the MCC redirection information and/or the extended5GMM cause IE. For example, the message 708 may include any of thereject causes (a)-(d) described above. The NAS response messageindicates that the UE is not allowed to access a core network of thefirst NTN. The NAS response message may further indicate that the UE isnot allowed to access the core network of the first NTN because alocation of the UE is unknown to the first NTN, that access to the firstNTN is not allowed in a country in which the UE is located, or that alocation of the UE is not within a country associated with the firstNTN. The NAS response message may indicate a first MCC of a firstcountry associated with the first NTN and may indicate that the UE isnot located within the first country. The MCC redirection informationmay indicate a first MCC for which the UE is eligible to obtain NTNaccess.

At 710, the UE modifies its PLMN search and/or registration behaviorresponsive to receiving the NAS response message 708. In someembodiments, responsive to receiving the NAS response message, the UEmay update its 5G status to a ROAMING NOT ALLOWED state for NTN access,wherein the UE refrains from performing PLMN search and registrationprocedures while in the ROAMING NOT ALLOWED state. In some embodiments,the UE may perform a search to access a terrestrial network responsiveto receiving the NAS response message. In some embodiments, the UE maysuccessfully establish a connection with a first terrestrial network,and perform a second NAS procedure (e.g., a registration or servicerequest procedure) with the first PLMN, where the UE provides anidentifier of the first terrestrial network to the first NTN during thesecond NAS procedure. The identifier of the first terrestrial networkmay be useable by the first NTN to determine a location of the UE.Alternatively or additionally, the UE may disable registrationprocedures for the first NTN for a predetermined period of time.

In some embodiments, when the NAS response message indicates the firstMCC of the first country associated with the first NTN and indicatesthat the UE is not located within the first country, the UE may modifyits behavior by disabling NTN access for the first MCC and initiating aPLMN search for NTN networks other than the first NTN belonging to adifferent MCC.

In some embodiments, when the NAS response message indicates an MCC forwhich the UE is eligible to obtain NTN access, the UE may modify itsbehavior by performing a second NAS procedure (e.g., a registration orservice request procedure) with a second PLMN of a second NTN associatedwith the first MCC. Alternatively, the 5GMM/reject causes may becommunicated to the UE using other NAS messages.

FIG. 9—PLMN Selection in International Areas

Satellite access networks cover large portions of the globe, includinginternational areas. In some deployments, specific legal requirements(e.g., SA3-LI) may be mandated in international areas, such as that anysolution addressing extraterritorial (e.g., international maritime zoneand aeronautical) use cases may be required to provide means for atravelling UE to notify its HPLMN on roaming in and out of those areas.

Embodiments herein present methods and devices to accommodate legal andregulatory requirements, while also improving connectivity and the userexperience. For example, methods are described to facilitate PLMNselection when a UE determines that it is in an international area, andthe UE may utilize information to aid in PLMN selection for NTN access.The information may be pre-configured in the UE or it may be provided bythe PLMN, in various embodiments.

In some embodiments, a UE may be travelling through an internationalarea, for example, a user may be traveling in a cruise from Australia toNew Zealand. The international area may be serviced by a dedicatedsatellite D1. The traveling UE may have a home PLMN in country A, or theUE may be roaming on a PLMN in country A (e.g., country A may beAustralia in this example, which may be either the home country or aroaming country of the UE).

FIG. 9 is a flow chart diagram illustrating a method for a UE tocommunicate with an NTN that is dedicated to servicing an internationalarea, according to some embodiments. Aspects of the method of FIG. 9 maybe implemented by a wireless device, such as the UE(s) 106, incommunication with a network, e.g., via one or more base stations (e.g.,BS 102) as illustrated in and described with respect to the Figures, ormore generally in conjunction with any of the computer systems ordevices shown in the Figures, among other circuitry, systems, devices,elements, or components shown in the Figures, among other devices, asdesired. For example, one or more processors (or processing elements) ofthe UE (e.g., processor(s) 302, baseband processor(s), processor(s)associated with communication circuitry, etc., among variouspossibilities) may cause the UE to perform some or all of theillustrated method elements. Similarly, one or more processors (orprocessing elements) of the BS (e.g., processor(s) 404, basebandprocessor(s), processor(s) associated with communication circuitry,etc., among various possibilities) may cause the UE to perform some orall of the illustrated method elements. In some embodiments, the UE maycommunicate directly with a base station, and the base station may inturn communicate with an access mobility function (AMF) of a 5GC thatservices the PLMN of the NTN. Note that while at least some elements ofthe method are described in a manner relating to the use ofcommunication techniques and/or features associated with 3GPPspecification documents, such description is not intended to be limitingto the disclosure, and aspects of the method may be used in any suitablewireless communication system, as desired. In various embodiments, someof the elements of the methods shown may be performed concurrently, in adifferent order than shown, may be substituted for by other methodelements, or may be omitted. Additional method elements may also beperformed as desired. As shown, the method may operate as follows.

At 902, a satellite of an NTN transmits a downlink message including anIE which states whether it is a dedicated satellite for an internationalarea. For example, the IE may be a one-bit true/false indicator thatdeclares whether the satellite is dedicated to servicing aninternational area. The downlink message may be a broadcast message, adedicated non-access stratum (NAS) message, or another type of downlinkmessage, in various embodiments.

In some embodiments, the satellite transmits a downlink message thatspecifies one or more prioritized lists of PLMNs. The message may be thesame message transmitted at step 902, or it may be a separate type ofbroadcast or other downlink message. The downlink message mayadditionally specify a polygon geofence or coordinates describing one ormore geographical regions within which the UE is to utilize the one ormore prioritized lists of PLMNs for performing PLMN selection.

In some embodiments, the satellite transmits a downlink message thatspecifies a first factor by which the UE modifies a search timerperiodicity for the first PLMN, where the first factor is selected basedat least in part on a satellite type servicing the NTN. The message maybe the same message transmitted at step 902, or it may be a separatemessage. When the satellite type is geosynchronous equatorial orbit(GEO), the first factor may decrease the search timer periodicity, andwhen the satellite type is low earth orbit (LEO) or high-altitudepseudo-satellite (HAPS), the first factor may increase the search timerperiodicity.

At 904, responsive to receiving the indication that the satellite isdedicated to servicing an international area, a UE may determine itsphysical location (e.g., using GPS, GNSS, context from a serving basestation, or other methods).

At 906, the UE determines whether it is in an international area. Forexample, the UE may compare its location to a polygon geofence oranother type of map provided by the network to determine whether it isin an international area. The polygon geofence may describe ageographical extent of the international area, and it may be receivedwithin a steering of roaming (SoR) container from the NTN that isprovisioned by the HPLMN of the UE. Determining whether the currentlocation is in the international area may include determining whetherthe current location is within the geographical extent of the polygongeofence.

At 908, the UE may indicate to a network during a registration procedure(e.g., either an initial registration or a mobility registrationupdating procedure) whether it is in the international area. Forexample, the UE may include an IE in a REGISTRATION REQUEST or MOBILITYREGISTRATION UPDATE message indicating whether it is in an internationalarea. The indication of whether the UE is in the international area maybe provided by the serving PLMN to the HPLMN of the UE. For example, theAMF servicing the UE may inform the HPLMN of the UE that the UE is inthe international area, to comply with regulatory requirements.

In some embodiments, the UE may store a reference point, which is thegeographical location or coordinates at which the UE enters aninternational area/waters from a contiguous area/waters. When the UEcrosses the reference point, the UE may start tracking its distance fromthe reference point.

In some embodiments, the UE may retrieve information indicating aprovisioned distance from the border of country A, or from the border ofcountry A's contiguous waters, within which the UE may use country A'sMCC while in the international area. For example, FIGS. 10A-B illustratea provisioned distance away from country A or its contiguousarea/waters, in various embodiments. The information indicating theprovisioned distance may be received from its home PLMN, it may bereceived in a broadcast from the NTN servicing the international area,or it may be retrieved from a local database of the UE (e.g., from theUSIM or other memory of the UE). While the UE is within the provisioneddistance from the reference point, the UE may use country A's MCC. Whenthe UE moves outside of the provisioned distance from the referencepoint, the UE may perform a prioritized PLMN search to select to a highpriority PLMN in the international area. The prioritized PLMN search mayprioritize the PLMN that is dedicated to servicing the internationalarea, as one example.

In some embodiments, the UE may utilize a polygon geofence to directPLMN selection. For example, the UE may compare the distance from thereference point with the geofence coordinates to determine whether it iswithin the geofence, and hence whether to stay with its current servingPLMN or to select another PLMN in the international area. In someembodiments, the geofence may define boundaries of multiple differentgeographical regions, and each region may be associated with aparticular priority ranking for performing a PLMN search. The UE maythen perform a PLMN search for NTN access according to the priorityranking of the region where it is currently located. The polygongeofence may be defined based on a distance in one or more directionsfrom the reference point, based on latitude and longitude coordinates,based on a collection of latitudes and longitudes to provide ageographical map, or based on any another methodology, as desired.

TABLE 1 Geofence Region PLMN Validity List Country A Country CountryCountry (serving PLMN) B C D Distance Point A Valid X X X 100 NM Point BX Valid X X  35 NM Point C X X X Valid  75 NM

Table 1 illustrates a PLMN validity matrix for points at differentdistances from the reference point. In Table 1, “NM” stands for nauticalmiles. As illustrated, from point A up to a radius of 100 NM aroundpoint A, country A′s PLMN(s) shall be considered valid, while the PLMNsof countries B, C and D are not considered valid. Conversely, from pointB up to a radius of 35 NM around point B, the PLMNs of country B areconsidered valid, whereas from point C up to a radius of 75 NM aroundpoint C, the PLMNs of country D are valid. Reference points A, B and Cmay be identified based on latitude and longitude, for example.

Methods for Handling Shared and Global PLMN IDs

In some implementations, PLMN IDs with the format MCC=9xx are reservedfor shared/global PLMNs. These PLMNs are not associated with anyparticular country and may be assigned by the InternationalTelecommunication Union (ITU). Satellite access networks providingcoverage globally typically use these PLMN IDs. Legacy PLMN selectionprocedures may not fully accommodate shared/global PLMN IDs. Forexample, a UE typically searches for higher priority PLMNs with the sameMCC as their currently selected VPLMN. Accordingly, a UE served by aVPLMN may not typically re-select to a PLMN using a global/shared MCC,and vice-versa. To address these and other concerns, modifications areproposed to the PLMN selection procedure to handle shared/global PLMNIDs.

In some embodiments, when a native MCC for a UE is available in cellularcoverage, the UE may prioritize the cellular MCC so the UE can movefreely between terrestrial and NTN access with LEO coverage on aregistered PLMN (RPLMN).

When cellular MCC coverage is not available, if the shared PLMN mappingto the PLMN list includes the HPLMN, the shared PLMN may have the samepriority as the HPLMN. Otherwise, the shared PLMN may be assigned thepriority of the lower VPLMN of all listed PLMNs in the PLMN list.

In some embodiments, a UE may prioritize an NTN PLMN when the UE hassufficient battery remaining, but may switch to prioritizing terrestrialPLMNs when the battery life drops below a threshold. The NTN PLMN andthe terrestrial PLMNs may be equivalent home PLMNs (EHPLMNs), preferredPLMNs (PPLMNs) (i.e., user PLMNs (UPLMNs)), or operator PLMNs (OPLMNs),among other possibilities.

In various embodiments, information to aid in handling shared/globalPLMN IDs (e.g., a mapping table) may be pre-configured in the UE orprovided by a PLMN.

In some embodiments, a UE may be configurable with different settings toprioritize or deprioritize NTN NG-RAN communications. For example, afirst configuration setting may prioritize NTN NG-RAN over cellular(terrestrial) NG-RAN (e.g., 5G NR), whereas a second configuration mayprioritize cellular NG-RAN over NTN NG-RAN. A third configurationsetting may disable NTN NG-RAN. The configuration setting may be storedin a USIM of the UE, and the configuration setting may specify, for eachof one or more MCCs, whether the UE is allowed access NTN NG-RAN and/orwhether NTN NG-RAN is preferred over cellular NG-RAN. The UE may thenutilize the configuration setting as part of its internal RATprioritization logic.

Alternatively, in some embodiments the NW may provide the configurationsetting, e.g., within a registration accept message or a configurationupdate message. Alternatively, configuration setting information may beprovided at the access stratum level via radio resource control (RRC)redirection signaling. In some embodiments, the application function(AF) may provide the configuration setting to a registered PLMN (RPLMN)AMF to be forwarded to the UE.

Search Timer Modification for PLMN Search

In some embodiments, a UE may modify its search timer behavior fordifferent types of NTN access. For example, for the high priority PLMN(HPPLMN), the UE may maintain a normal (i.e., default) search timerperiodicity. The UE may receive a scaling factor m(sat) that modifiesthe search timer periodicity for different types of NTNs. The scalingfactor may be retrieved from the USIM of the UE or the UE's internalmemory, or it may be received from a steering of roaming (SoR)container) provided by the HPLMN. In some embodiments, m(sat) is a 4-bit(or another number of bits) multiplier that specifies a factor from theset { 1/16, ⅛, ¼, ½, 0, 1, 2, 4, 8, 16} (or another set of values) withwhich to modify the PLMN search periodicity. The scaling factor mayincrease the search frequency for PLMNs corresponding to low earth orbit(LEO) satellites and high-altitude pseudo-satellites (HAPS), and maydecrease the search frequency for PLMNs corresponding to geosynchronousequatorial orbit (GEO) satellites, relative to the search frequency forthe HPPLMN. PLMNs for medium earth orbit (MEO) satellites may utilize anm(sat) value that is intermediate between those used for LEO and GEOsatellites, in some embodiments. A value of m=0 may be used to cause aUE to refrain from performing any searches for NTN access for aparticular type of NTN access, and this type of NTN access may beacquired exclusively through handover or reselection processes. Thesteering of roaming information may also provide the priority PLMN listfor utilization in international areas.

FIG. 11 illustrates a scenario where a user in a plane travels from theU.S. to India, passing through LEO coverage areas of countries A, B, C,D and E during the flight. Additionally a GEO satellite provides broadercoverage to the indicated region with a global/shared PLMN. In someembodiments, the UE may search for PLMNs of the LEO satellites with alower frequency, since the UE will move into and out of these smallercoverage areas in a shorter amount of time, whereas the UE may performsearches with a higher frequency on the PLMN of the GEO satellite.

TABLE 2 OPLMN Priority Table—Example 1 Priority OPLMN RAT Note 1 910-410NR SAT NTN PLMN allowed in country 310 2 405-829 NR, LTE Differentcountry, no search needed 3 310-210 NR UE camped on this PLMN 4 316-211NR Low priority PLMN of same country

Table 2 illustrates an example priority table for OPLMN selection. Asillustrated, a UE is currently camped on OPLMN 310-210 with a priorityrank of 3. OPLMN 910-410 provides NTN access which is allowed in country310, and is given the highest priority ranking. OPLMN 405-829corresponds to a different country, and is not searched by the UE. OPLMN316-211 is a low priority PLMN of country 310, and has a priority rankof 4. In some embodiments, the search timer for the 910-410 OPLMN may beincreased from its default value (e.g., 6 minutes) by an m(sat) factorof 10 such that the OPLMN 910-410 is only searched every 60 minutes, asone example.

TABLE 3 OPLMN Priority Table—Example 2 Priority OPLMN RAT Note 1 310-410NR SAT NTN PLMN allowed in country 310 2 310-266 NR, LTE Terrestrialnetwork in the same country 3 310-210 NR UE camped on this PLMN 4316-211 NR Low priority PLMN of same country

Table 3 illustrates another example priority table for OPLMN selection.As shown, a UE is currently camped on OPLMN 310-210 with a priority rankof 3. OPLMN 310-410 provides NTN access which is allowed in country 310,and is given the highest priority ranking. OPLMN 310-266 corresponds toa terrestrial network in the same country where the UE is currentlycamped. OPLMN 316-211 is a low priority PLMN of country 310, and has apriority rank of 4. In some embodiments, the search timer may continueto be the same existing HPPLMN search timer as the UE performs searchesfor terrestrial networks.

Embodiments of the present disclosure may be realized in any of variousforms. For example, some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of the methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE) may be configured to includea processor (or a set of processors) and a memory medium, where thememory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement anyof the various method embodiments described herein (or, any combinationof the method embodiments described herein, or, any subset of any of themethod embodiments described herein, or, any combination of suchsubsets). The device may be realized in any of various forms.

In some embodiments, a device includes: an antenna; a radio coupled tothe antenna; and a processing element coupled to the radio. The devicemay be configured to implement any of the method embodiments describedabove.

In some embodiments, a memory medium may store program instructionsthat, when executed, cause a device to implement any of the methodembodiments described above.

In some embodiments, an apparatus includes: at least one processor(e.g., in communication with a memory), that is configured to implementany of the method embodiments described above.

In some embodiments, a method includes any action or combination ofactions as substantially described herein in the Detailed Descriptionand claims.

In some embodiments, a method is performed as substantially describedherein with reference to each or any combination of the Figurescontained herein, with reference to each or any combination ofparagraphs in the Detailed Description, with reference to each or anycombination of Figures and/or Detailed Description, or with reference toeach or any combination of the claims.

In some embodiments, a wireless device is configured to perform anyaction or combination of actions as substantially described herein inthe Detailed Description, Figures, and/or claims.

In some embodiments, a wireless device includes any component orcombination of components as described herein in the DetailedDescription and/or Figures as included in a wireless device.

In some embodiments, a non-volatile computer-readable medium may storeinstructions that, when executed, cause the performance of any action orcombination of actions as substantially described herein in the DetailedDescription and/or Figures.

In some embodiments, an integrated circuit is configured to perform anyaction or combination of actions as substantially described herein inthe Detailed Description and/or Figures.

In some embodiments, a mobile station is configured to perform anyaction or combination of actions as substantially described herein inthe Detailed Description and/or Figures.

In some embodiments, a mobile station includes any component orcombination of components as described herein in the DetailedDescription and/or Figures as included in a mobile station.

In some embodiments, a mobile device is configured to perform any actionor combination of actions as substantially described herein in theDetailed Description and/or Figures.

In some embodiments, a mobile device includes any component orcombination of components as described herein in the DetailedDescription and/or Figures as included in a mobile device.

In some embodiments, a network node is configured to perform any actionor combination of actions as substantially described herein in theDetailed Description and/or Figures.

In some embodiments, a network node includes any component orcombination of components as described herein in the DetailedDescription and/or Figures as included in a mobile device.

In some embodiments, a base station is configured to perform any actionor combination of actions as substantially described herein in theDetailed Description and/or Figures.

In some embodiments, a base station includes any component orcombination of components as described herein in the DetailedDescription and/or Figures as included in a mobile device.

In some embodiments, a 5G NR network node or base station is configuredto perform any action or combination of actions as substantiallydescribed herein in the Detailed Description and/or Figures.

In some embodiments, a 5G NR network node or base station includes anycomponent or combination of components as described herein in theDetailed Description and/or Figures as included in a mobile device.

It is well understood that the use of personally identifiableinformation should follow privacy policies and practices that aregenerally recognized as meeting or exceeding industry or governmentalrequirements for maintaining the privacy of users. In particular,personally identifiable information data should be managed and handledso as to minimize risks of unintentional or unauthorized access or use,and the nature of authorized use should be clearly indicated to users.

Any of the methods described herein for operating a user equipment (UE)may be the basis of a corresponding method for operating a base station,by interpreting each message/signal X received by the UE in the downlinkas message/signal X transmitted by the base station, and eachmessage/signal Y transmitted in the uplink by the UE as a message/signalY received by the base station.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A method, comprising: by a user equipment (UE):performing a first non-access stratum (NAS) procedure with a firstpublic land mobile network (PLMN) of a first non-terrestrial network(NTN); receiving a NAS response message from the first PLMN, wherein theNAS response message indicates that the UE is not allowed to access acore network of the first NTN; and responsive to receiving the NASresponse message, performing a search to access a terrestrial network.2. The method of claim 1, the method further comprising: successfullyestablishing a connection with a first terrestrial network; performing asecond NAS procedure with the first PLMN, wherein the UE provides anidentifier of the first terrestrial network to the first NTN during thesecond NAS procedure, and wherein the identifier is useable by the firstNTN to determine a location of the UE.
 3. The method of claim 1, whereinthe NAS response message further indicates one of: that the UE is notallowed to access the core network of the first NTN because a locationof the UE is unknown to the first NTN; that access to the first NTN isnot allowed in a country in which the UE is located; or that a locationof the UE is not within a country associated with the first NTN.
 4. Themethod of claim 1, the method further comprising: further responsive toreceiving the NAS response message, disabling NAS procedure for thefirst NTN for a predetermined period of time.
 5. The method of claim 1,wherein the NAS response message indicates a first mobile country code(MCC) of a country associated with the first NTN and indicates that theUE is not located within the country, wherein the method furthercomprises: disabling NTN access for the first MCC; and initiating a PLMNsearch for NTN networks with MCCs different from the first MCC.
 6. Themethod of claim 1, the method further comprising: further responsive toreceiving the NAS response message, update a 5G status of the UE toROAMING NOT ALLOWED for NTN access.
 7. The method of claim 1, whereinthe NAS response message further indicates a first mobile country code(MCC) for which the UE is eligible to obtain NTN access, the methodfurther comprising: performing a second NAS procedure with a second PLMNof a second NTN associated with the first MCC.
 8. The method of claim 1,wherein the NAS procedure comprises: an initial registration procedure,a mobility registration update procedure, or a service requestprocedure, and wherein the NAS response message comprises: aderegistration request message, a service rejection message, or aregistration rejection message.
 9. A user equipment (UE), comprising: aradio; and a processor operably coupled to the radio, wherein the UE isconfigured to: perform a first non-access stratum (NAS) procedure with afirst public land mobile network (PLMN) of a first non-terrestrialnetwork (NTN); receive a NAS response message from the first PLMN,wherein the NAS response message indicates that the UE is not allowed toaccess a core network of the first NTN; and responsive to receiving theNAS response message, initiate a second NAS procedure with a second PLMNof a second NTN belonging to a second country that is different from afirst country of the first NTN.
 10. The UE of claim 9, wherein the UE isfurther configured to: perform a search to access a terrestrial network;successfully establish a connection with a first terrestrial network;perform a third NAS procedure with the first PLMN, wherein the UEprovides an identifier of the first terrestrial network to the first NTNduring the second NAS procedure, and wherein the identifier is useableby the first NTN to determine a location of the UE.
 11. The UE of claim9, wherein the NAS response message further indicates one of: that theUE is not allowed to access the core network of the first NTN because alocation of the UE is unknown to the first NTN; that access to the firstNTN is not allowed in a country in which the UE is located; or that alocation of the UE is not within the first country of the first NTN. 12.The UE of claim 9, wherein the UE is further configured to: furtherresponsive to receiving the NAS response message, disable first NTNaccess at the UE for a predetermined period of time.
 13. The UE of claim9, wherein the NAS response message indicates a first mobile countrycode (MCC) of the first country of the first NTN and indicates that theUE is not located within the first country, wherein the UE is furtherconfigured to: disable NTN access for the first MCC; and initiate a PLMNsearch for NTN networks with MCCs different than the first MCC.
 14. TheUE of claim 9, wherein the NAS response message further indicates amobile country code (MCC) for which the UE is eligible to obtain NTNaccess, wherein the MCC is an MCC of the second country.
 15. An accessand mobility management function (AMF) servicing a first public landmobile network (PLMN) of a first non-terrestrial network (NTN), the AMFcomprising: a network port; and a processor coupled to the network port,wherein the AMF is configured to: receive a NAS request message from auser equipment (UE), wherein the NAS request message includes locationinformation of the UE; transmit a request message to a core network ofthe first NTN, wherein the request message includes the locationinformation; receive a response message from the core network; andtransmit a NAS response message to the UE, wherein the NAS responsemessage indicates that the UE is not allowed to access the first NTN.16. The AMF of claim 15, wherein the location information comprises anidentifier of a first terrestrial network registered with the UE,wherein the first terrestrial network is associated with a firstcountry.
 17. The AMF of claim 15, wherein the NAS response messagespecifies that access to the first NTN is not allowed in a countryspecified by the location information.
 18. The AMF of claim 15, whereinthe NAS response message specifies that the location informationspecifies a location that is not within a first country associated withthe first NTN, and wherein the NAS response message further specifies amobile country code (MCC) of a second country for which the UE iseligible for NTN access.
 19. The AMF of claim 15, wherein the NASresponse message indicates a first mobile country code (MCC) of a firstcountry associated with the first NTN and indicates that the UE is notlocated within the first country.
 20. The AMF of claim 15, wherein theNAS request message comprises: an initial registration procedure, amobility registration update request, or a service request, and whereinthe NAS response message comprises: a deregistration request message, aservice rejection message, or a registration rejection message.